Construction work machines such as hydraulic excavators (hereinafter referred to as “construction machines”) in recent years have been made more intelligent through the provision of high performance computers and high performance programs and have been made able to utilize communication satellites, the Internet, and other telecommunication lines for the transfer information, instructions, etc. between construction machines deployed at far off work sites and a central base station (center server) for systemization based on centralized control.
On the other hand, in recent years, cases of theft of hydraulic excavators have been increasing. Hydraulic excavators are deployed at far off work sites as explained above. The engines of the hydraulic excavators are stopped when not performing work and the machines left at the sites. The machines are not monitored that strictly system-wise. Therefore, they are easy to steal.
Therefore, as a conventional system for reliably preventing the theft of construction machines as explained above, for example, the “theft prevention apparatus and theft prevention system for construction machines” disclosed in Japanese Patent Publication (A) No. 2000-73411 have been proposed.
This system is a theft prevention system designed to compare identification information given to a construction machine with identification information input for operation when operating the construction machine and, when judging that the result of comparison is that they “do not match”, to cut the circuit for powering up the starter circuit and the circuit for supplying hydraulics to the remote control valve for running motor operation or the feed path for feeding fuel to the engine so as to prevent the starter motor from being started up. This theft prevention system uses the special features in the design of the electrical system, hydraulic system, and fuel feed system in hydraulic excavators to make the conditions for startup more complicated and increase the difficulty of theft.
Further, in the above theft prevention system, it is possible to add to a construction machine equipped with such a theft prevention system the function of determination of the location of the construction machine utilizing a GPS (Global Positioning System) and preventing startup as explained above by sending an operation shutdown signal from a sending station to the construction machine when the construction machine is located other than at its predetermined work area. Further, it is possible to make a display of a PC of a manager of the construction machine display a map showing a circle of the work site of the construction machine, display information showing the location of the construction machine superposed on that map, and enable confirmation as to if the location of the construction machine managed by the manager is in the usual work area. When the construction machine is outside of the work area on the map, it is possible to raise an alarm and send an engine shutdown signal.
However, in the conventional theft prevention system, while it is possible to make the startup conditions of the starter motor more complicated to increase the difficulty of theft, it is not possible to completely prevent the theft. Further, while a manager can learn that the construction machine has been stolen when located outside of the work area on the map, after this it is not possible to then learn the location of the construction machine outside of the work area.
An object of the present invention, in view of the above problem, is to provide a location confirmation method and location display system of a construction machine and such a construction machine enabling the construction machine itself to periodically calculate its own current location data and send the current location data and measurement time data to enable its location and changes in location along with time to be confirmed on a map when the construction machine moves, enable movement of the construction machine to be tracked, and help confirm its location and prevent theft.